sCIeNCeNS 1.6.1 Verify accuracy of observations. NS 1.7.1 Interpret evidence based on observations. ESS 8.8.16 Identify components of soil as inorganic or organic through investigations.ESS 8.8.18 Identify ways plants use organic and inorganic components in the soil.ESS 8.8.19 Investigate and analyze the composition of a variety of soils.
LaNGUaGe arTsOV 1.6.6 Contribute appropriately to class discussion.OV 1.7.6 Contribute appropriately to class discussion.OV 1.8.6 Contribute appropriately to class discussion.
s objeCTIvesThe students will learn:
objeCTIve #1 To describe acidity and alkalinity in soil.
objeCTIve #2 To read a pH scale.
objeCTIve #3 To define the role of pH levels in soil.
objeCTIve #4 To determine pH levels in soil samples.
objeCTIve #5 To describe the relationship between pH level and healthy plants.
objeCTIve #6 To appropriately use verbal speaking skills in class discussion with the teacher and Garden Program Specialist.
Page 2 EARTH SYSTEMS • Sweet ‘N Sour: Teachers’ Guide
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elopment, and its most important function, photosynthesis. overvIewSoil pH, an indicator of soil chemistry, affects the availability of important nutrients to plants. The pH scale ranges from 1 (most acid) to 14 (most basic or alkaline), with 7 being neutral. Most plants prefer mildly acidic soil. Soil can be amended to change the pH level.
GardeN aCTIvITIes▲s Testing the pH level in soil samples
▲s Plant, harvest and work in the garden following the Garden Guide
▲s Recipes and Taste tests as time permits (refer to Delta Garden Study Recipe Book)
Page 4 EARTH SYSTEMS • Sweet ‘N Sour: Teachers’ Guide
LessoN pLaN
I. Start in the classrooma. Icebreaker
Ask students: “How many varieties of rice are there in the world?”
ANSWER: “Rice has more varieties than any other fruit or veg-etable, nearly 15,000! Many countries have a few specific variet-ies of rice that cannot be found anywhere else. There are about 5,000 varieties of tomato, and 7,500 varieties of apples.”
b. present main Topic▲s Explain and define acidity and alkalinity. meeTs objeCTIve #1▲s Show the Visual and explain how a pH scale works. meeTs objeCTIve #2
II. Take class to the garden▲s Instruct the students to collect soil samples and measure pH levels
as described in the Supporting Information for Teachers pages. Discuss the relationship between soil pH level and healthy plant growth, bud and fruit development and photosynthesis.
meeTs objeCTIves #3–5
▲s Instruct students to plant, harvest and work in the garden following the Garden Guide.
▲s Pick and taste available vegetables. As appropriate, classify edible crops as alkaline- or acid-soil-loving plants.
meeTs objeCTIve #5
III. Take class back to classroom▲s Hand out the Student Learning Workbook as reference material
and class assignment. Review take it home activities and encourage students to do them.
EARTH SYSTEMS • Sweet ‘N Sour: Teachers’ Guide Page 5
sUpporTING INFormaTIoN For TeaChers
baCkGroUNd
Soils typically range in pH between 4 and 9. Most plants do well in slightly acidic soil, with 6.5 or 6.6 being the optimum pH level. If the soil is too acidic, many soil minerals dissolve and become so concentrated that they are toxic to plants. If the soil is too alkaline, minerals don’t dissolve enough and the plants can’t absorb them.
When the pH level is right, countless micro-organisms are at work maintaining the health of the soil. Micro-organisms provide nutrients to the plant’s root system. Typically, they change the organic forms of two main nutrients found in decayed plant and animal matter, nitrogen and phosphorus, into inorganic forms; they “mineralize” them. Put simply, the nutrients’ chemical structure changes during this process of going from organic to inorganic. Plants need these nutrients, and also another major one called potassium, in this inorganic form. Without these nutrients, plants couldn’t grow, couldn’t form buds or fruits, and couldn’t perform their most important function—photosynthesis. As you’ll recall, photosynthesis is the process of taking light from the sun, carbon dioxide from the air and water to make glucose (the plant’s food) and oxygen. We couldn’t live if we didn’t have the oxygen produced by plants.
The right pH level of soil is essential for healthy plant growth, development of buds and fruits, and photosynthesis.
aCTIvITIes
A basic reading of soil pH can be obtained with blue and red litmus paper.
Acids turn blue litmus paper red.
Bases turn red litmus paper blue.
ph analysis:
Materials needed
▲s trowels or spades to dig up small amounts of soil
▲s small plastic bags or cups
▲s markers
▲s masking tape
▲s petri dishes (or similar)
▲s eye droppers
▲s blue and red litmus paper (pH paper)
Procedure
1. Instruct students to work in small groups.
2. Instruct each group to dig up small amounts of soil (1 cup each) from various locations on the garden/school grounds. Be sure the samples are collected from a wide variety of places. Students should dig down 5-7 inches deep without harming surrounding plants.
3. The soil should be placed in the plastic bags and its location and the names of plants there (if any) should be noted using the Magic Markers and masking tape.
4. For each sample taken, instruct the students to place a piece of blue litmus paper in one petri dish and a piece of red litmus paper in the other. The students should then place about ½ teaspoon of their soil sample on top of each strip.
5. Using the eyedropper, the students should then moisten the soil until the strips of litmus paper become wet.
6. Finally, instruct the students to brush the soil away. Is their soil acidic or basic?
7. Discuss whether soil samples collected from beds with edible crops differ from each other and from others collected at other locations.
▲✚ optional activity:
If soil sample test results (taken during the lesson Everything Matters) are available, examine the pH report in the soil sample test results and discuss the results with students.
8. Consider the following questions:
▲s Where do the soil samples fall along the pH scale? Are they acidic or alkaline?
▲s Are they appropriate levels for growing plants?
▲s How might these pH levels affect plant growth or how/where we plant?
▲s What are some other ways to address unsuitable pH levels? (i.e., amending soil or planting according to specific pH levels)
Page 6 EARTH SYSTEMS • Sweet ‘N Sour: Teachers’ Guide
soUrCes
The ABCs of Ecology, An Educator’s Guide to Learning Outsideby Ecology Education, Inc., 2006
United states department of agriculture, Natural resources Conservation servicehttp://soils.usda.gov/education/resources/lessons/profile/
Master Gardener Arkansas HandbookUniversity of Arkansas, Division of Agriculture, Cooperative Extension Service, 2000
botanic Gardens Conservation International, Canada, (bGCI) Investing in Nature, a partnership for plants in Canadahttp://www.bgci.org/files/Canada/english_docs/rbg_soilph.pdf
hands-on science (Laurel F. appel)http://lappel.web.wesleyan.edu/expts.htm
Colorado state University extensionhttp://www.ext.colostate.edu/mg/gardennotes/222.html
study guide for studentsYou’ve learned that soil components are minerals, organic matter, air and water. You have also learned how soil is classified by texture, structure, profile and color. And, in the last lesson, you learned that the soil contains micronutrients and macronutrients in the form of minerals, such as phosphorus, nitrogen, and iron. Now we will consider the acidity of soil.
You are probably familiar with acids like vinegar in pickles or citric acid in oranges and lemons. The opposite of acidic is alkaline. Substances that are more alkaline include laundry detergent and baking soda. Soil can be acidic or alkaline as well! The level of acidity and alkaline in a substance like soil can be tested with special methods and measured on a scale called the pH scale. The scale is logarithmic, so an element with a pH of 8 is 10 times more alkaline than an element with a pH of 7, and an element with a pH of 4 is 10 times more acidic than an element of a pH of 5.
Soils typically range in pH between 4 and 9. Most plants do well in slightly acidic soil, with 6.5 or 6.6 being the optimum pH level. If the soil is too acidic, many soil minerals dissolve and become so concentrated that they are toxic to plants. If the soil is too alkaline, minerals don’t dissolve enough and the plants can’t absorb them.
When the pH level is right, countless microorganisms are at work maintaining the health of the soil. Microorganisms provide nutrients to the plant’s root system. Typically, they change the organic forms of two main nutrients found in decayed plant and animal matter, nitrogen and phosphorus, into inorganic forms; they “mineralize” them. Put simply, the nutrients’ chemical structure changes during this process of going from organic to
inorganic. Plants need these nutrients, and also another major one called potassium, in this inorganic form. Without these nutrients, plants couldn’t grow, couldn’t form buds or fruits, and couldn’t perform their most important function—photosynthesis. As you’ll recall, photosynthesis is the process of taking light from
the sun, carbon dioxide from the air and water to make glucose (the plant’s food) and oxygen. We couldn’t live if we didn’t have the oxygen produced by plants.
You can determine the soil’s pH level with soil kits or get a basic reading with litmus paper. Once you know the results, you can improve the soil somewhat to change its chemistry. Adding limestone can lower the pH level, adding sulfur, can raise it.
acidic pH levels ranging from 0-6alkaline also known as base, pH levels ranging from 8-14 inorganic not alive and none of its components have ever been aliveorganic anything that is or has ever been alivelitmus paper a strip of paper that can test the pH level of substances
ESS 8.8.19 Identify ways plants use organic and inorganic components in the soil.
1. In the table below, indicate whether each plant’s ideal ph is an acid or base. Then record those plants in next to the appropriate number on the provided ph scale.
Plant Ideal pH Is this plant’s ideal pH acid or alkaline/base?
Artichoke 7.5
Basil 6
Blueberry 5
Corn 6.5
Mint 8
Peanut 5.5
Watermelon 6
2. most soil ph ranges between ____ and _____, but the ideal soil ph for most plants is ____________. a. 4 and 9, 8.0
b. 4 and 9, 6.5
c. 1 and 14, 6.5
d. 1 and 14, 8.0
Take it HomePlants automatically absorb nutrients as long as growing
conditions are right. Make sure you are constantly choosing physical activity: walk to the
1. In the table below, indicate whether each plant’s ideal ph is an acid or base. Then record those plants in next to the appropriate number on the provided ph scale.
Plant Ideal pH Is this plant’s ideal pH acid or alkaline/base?
